Two-piece valve and method of making same



W. H. WASHEU- Two-Pimm VALVE AND METHOD 0F MAKING SAM Filed Ooi. 24,

jan, s E924 Patented Jan. l, 1924.

UNITED STATES PATENT YoFFIcE.

WILLIAM H. WASHBURNIE, OF CHICAGO, ILLINOIS, ASSIGNOR TO THE OLIVERTYPE- WRITER COMYANY, F CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TWO-PIECE VALVE AND METHOD OF MAKING Applicationled October 24, 1921.

Jul Improvement in Two-Piece Valves and- Methods of Making Same, anddeclare the following to be a tull, clear, and exact description of thesame, such as will enable others skilled in the art to which it pertainsto make and use `the same, reference being had to the accompanyingdrawings, whichl form a part of this specification.

It is desirable in puppet valves for internal combustion engines to havethe head made -out of a heat-resisting alloy -while the stem is made-out of a wear-resisting. or

friction-resisting alloy. Heretofore the com' mon' practice o makingvalves of this kind has been to screw the heads on thel ends of thestems and, after riveting over-.the ends of the stems somewhat, weldingthe heads and'stems together. This is not only an expensive processbutlit 'introduces welding stresses which frequentl cause warping in thestems just under the heads or close to the point -where the welds aremade. Consequentlyvalves Imade inthemannerjust de'- scribed are not onlyexpensive but they are frequently/defective. c Y The object of theApresent invention isto produce a perfectl two-part poppet valve in asimple and'no'vel way and at a low manufacturing cost.. 'f ,i Y

The various.;f eatures :of novelty whereby myA invention ischaracterized -will 'hereinafterbe pointed out with ,particularity inthe claims; but, for a full understanding of my invention and of its'object and advan- 40 tages, reference may be had to 'the' followingdetailed description taken in connection with the accompanying drawing,wherein:

Figure 1 is a vertical section through a pair .of forming dies' readyto-closeupon a 4.5l rudimentary valve head and-.fashion it andsecureglt, tol a stem held in position to receive it' .fa

tu the condition,-existing when the dies have been closednithef-workaand A Fig-3 is, iside. elevatfon ofthe completed valve-headandgtheadjacentportion of the Serial No. 509,948.

In accordance with my invention I first make' a finished stem, somethingwhich can be accomplished at a very low cost by automatic machinery intowhich is fed rod or heavy wire stock. A rudimentary head iS then placedon the end ot' a stein and is simultaneously forged into a completedhead and attached to the stem in such a manner that no stresses tendingto produce warping or distortion are produced, and permitting thecompleted valve to be placed directly in service after the singlefinishing operation of grinding the valve face.

Referring to the drawing, l represents the lower die and 2 the upper dieof a forging machine. The lower die has a central hole or chamber 3 intowhich a valve stem 4 accurately fits. The hole or chamber is closed atthe bottom so that the valve stem will rest on a solid support at itslower end. In the top of the lowerdie, co-axial with the hole 3, is amold cavity 5 having the shape of a completed valve-head. The bottom ofthe upper die may be simply a flat surface although there is preferablya central recess orI depression 6 slightly larger in diameter than thediameter of the valve stem, so as to insure thatthere will always be aclearance between thelupper end of the valve Stem and the upper die orbetweenthe upper die and any metal which might flow across the top ofthe valve stem from the rudimentary valve during the forging operation.

- That portion of the valve stem'which lies within the mold cavity 5when the stem is dropped into the lower die is provided with superficialirregularities adapted to interlock with the metal of lthe valve-head.These irregularities preferably take the form of an ordinary screwthread 7 extending throughout the length if that portion of the stemthat lies above the bottom of the mold cavity.

l/Vhile the valve stem is placed in the di in a finished condition, thehead, when placed in the die, is a mere rudimentary blank in the form ofa thick washer` as indicated at 8. The hole 9 in the blank -is madesomewhatlarger in dia-meter than the the stem and, instead of beingcylindrical, is preferably madey in the form of a frustum of a cone thesmaller 'end of which lies at diameter of the screw threaded portion ofper die forces the metal of the blank in the' fthe screw threads.

the bottom when the blank is placed in the machine. The thinnestportions of valves of the kind under consideration are the marginalportions and there is usually a grad ual increase in thicknessv towardthe center solthat the thickness or depth is greatest at the center. 3 Itherefore prefer to make the valve-head blank thickest at the middle anddecreasing gradually in thickness towardtlie periphery.

In buildinga valve, a stein'is dropped down into the lower die, the stembeing at ordinary room temperature. The for the head is heated to a hightemperature, preferably one approaching welding heat. The hot blank .isthen dropped into the mold cavity' in the lower die and the upper die isdriven down. 'he shape of the blank is such that in the first instanceit is supported only at the margin, so that as soon as the upper dieengages with the top ofthe blank it' starts to press the center of theblank down. Since the opening in the blank is larger in .diameter thanthe stein, the downward movement of the center of the blank takes placejust as though the stem were not present. Only after the bottom of theblank has been shaped to the mold cavity excepting only at the middlewhere the boss or hub in the completed valve is to appear, the continueddownward movement of the up# vicinity of the stem downwardly and alsoinwardly toward the axisot' the stein. As the metal flows down into thebottom portion 10 of the mold cavity which is for the purpose of givingshape to the hub or boss on the under side of the valve-head, it findsitself confined by a rigid surrounding wall and it `tlierefore can flowonly inwardly toward the axis of the valve` namely upon The definitevnim'f'nnent of the metal in the head toward 'the axis begins at thebottom and progresses toward the top so that it may be said that thehead is forged or molded so as to bringzit'pro-V gressively intointerlocking engagement with the screw threads oii the stein from thebottom of the head toward the-top. lThis is considered of importancebecause thev advantages secured from lie working of the metal of thehead in forging itA into shape are not lost through the creation ofshearing stresses which begin to shear away the metal of the head lyingnext to the valve stem ,while the downward flow or movement of t-le mainportion of tliemetal is taking p ace. upon the lower die there will or'course be a downward pressure on the metal ofthe head immediatelyad'aeent to and surrounding the stem, but t is will serve only to insureperfect contact at all times between the screw threads and' the metal ofthe head,v and there may also be a slight dis- When the upper die isfully closedtortion of the lowermost screw threads which will produce a.locking effect' if it be attempted to 'unscrew the head.

ject'ed to anforces which will alect it in any way, t e vprincipalstresses' that are applied to thestem being the radial stresses as thematerial of the head is forged inwardl toward the airis. 1t will also beseen t iat by for ing the head while heated toa degree whic permits'ittofiow readily under pressure, there-will be no unbalanced internalstresses which might produce warping or distortion after removal of thevalve 'from the dies. Consequently when the valve is removed from themold it is ready to beput into use asfsoon as it becomes cool, the onlyfinishing operation that is neces- It will be seen that the stern is notsub-A .l i

sarv being the grinding of the valve face 11.

Whenthe two parts of the valve are assembled in the pressthe differencein temperature between them is greater'. than it will ever bethereafter, the stem being pracf tically cold, namely atroomtemperature, and the valve being at 'approximately a welding heat.At the end ofthe for ing isted when both the stein and the headwerecold. Iii other Words, when the head cools f, thereby. maintaining therelative condition which exf after/the Valve has been. taken out ofl'the` dies',it shrinks and `increases its grip on the comparativelycool stein, which grip would be decreased if the head' coul ain beheated without correspondingly heating the stem, but which 'will remain.practically constant if the stem be heated at the same time that thehead is heated as is the case when the valve is put into service.

I claim:

1. The method of making a two-part valve which consists' in insertingthe '-screw threaded end of a stem into a cone-sha ed hole in avalveliead blank larger in diameter at the smaller end than the stem,and then forging the blank so as to cause the metal to flow toward thecenter and progressivelyA fill the screw threads in the stem beginninwith the threads inthe small end of the ho e and lsiinultaneousl-y giveto the blank the contour of a valve-head.

2. The methodof making a two-part valve which consists in resting oneend of a cold 4finished stem on a support, lcating a heated to the blankthe shape of a valve head, and

then completing the valve by grinding the valve face.

The method of making a two-part valve which consists in inserting a steminto a cone-shaped hole in a heated valve-head blank, and then forgingthe blank so as to.

cause the nietal to flow towards the center and pro ressively engagethestem from the portion ying adjacent to the smaller end of the hole tothat portion lying adjacent to the larger end of the hole andsimultaneously give to the blank the contour of a valve head.

4. The method of making a two-part valve which consists in inserting theend of a stem having grooves extending around the same, into acone-shaped hole in a hot valve-head blank larger in diameter at thesmaller vend than the stem, and then forging .the blank so as to causethe metal to flow toward the center and progressively fill the4 groovesin the stem'beginnin with the groove in the small end of the ole andsimultaneously give to the blank the contour of a valve head.

5. The method of making a two-part valve which consists in insertin astem into a hole of lar er diameter exten ing through a hot valve-lgieadblank, so as to leave the end of the stem exposed and free, and thenforging.

the blank. so as to cause the metal to flow towards the center intointimate contact with lthe stem and simultaneously give to the .blankthe sha e4 of a valve head, without v,exerting any orging end of thestem in the of the stem.

pressure on the said direction of the length 6. The method of makingatwo-part valve which consists in inserting a comparatively' cold steminto a hole of larger diameter extending' through a liilily heatedvalve-head blank, and then forging the blank to cause the metal to flowtoward the -center into intimate contact with the stem andsimultaneously ive to the blank the shape of a valve head withoutexerting any forging ressure on the stem in the eiigth ofthe stein. '7.The method of making a tw'oart valve which consists in inserting. ashoul ered portion of a stein into a hole of larger diameter extendingthrough a heatedvalve-head blank, and then forging the blank withoutexerting any forging pressure on the exdirection of the posed end of thestem,so as to cause theI metal to flow toward 'the center into intimatecontact with the stein and simultaneously give to the blank the contourof a valve head.

8. The method of making a twoart valve which consists in, inserting ashoul ered portion of a cold stein iito a hole of larger diameterextending through a highly heated valve-head blank so as io' leave anend of the stein adjacent to the blank free and exposed, and thenforging the Blank by exerting a. pressure on the saine only on thesurfaces thereof sui'rounding sa .d hole 'and without exerting anyforging pressure on-said exposed end of the stem so as to cause themetal to flow toward ihe center into'intimate contact with the stem andsimultaneously give to the blank the contour of al 4the stem is leftfree, to cause the metal of the blank to flow toward the center intointimate contact with the stem and: simultaneously give to the blank theshape of a valve head.

10. The vmethod of making .a twoart valve which consists in heating awas erlike blank of approximately the diameter of the valve to beformed, inserting in the hole iir the blank a part near one endof a.stem smaller in diameter than said hole, and then forging the blank indies one of which has a recess somewhat larger in diameter than the stemand adapted to register with' said end of the stemwhen the dies areclosed and'thus placing endwise forging pressure on avoid the stem..

11. The method of making a two-part valve which consists inresting oneerd of a 'cold stem on a support, locating a heated washer-like blank ofapproximately the diameter of the valve head to be formed so that itsurrounds the stem in the vicinty of the other. end and leaves thelatterend free and exposed, and then forging the blank without imposingany forging pressure on the last mentioned end of the stem so as tocause the metal of the blank to flow into intimate contact with thestein and simultaneously give tq'the blank the shape of a valve ead.

In testimony whereof, I sign .this specification.

WILLIAM H. WAsHBUInna`

